1. Field of the Invention
A method of manufacturing a wobble or swash plate assembly by a die-cast method.
2. Description of the Prior Art
The prior art is replete with techniques for the casting of metals, ceramics and plastics into various parts including ball and socket arrangements. These castings are frequently two element parts, such as a socket member cast about a ball so that the socket retains the ball and is movable about the ball. However, the use of die inserts to fix the relative location of such sockets in a multipart ball and socket assembly is not well known.
The casting of a fused quartz (ceramic) insulator about a ball-headed rod is disclosed in U.S. Pat. No. 1,680,705 to Thompson. A bimetal piston arrangement is taught in U.S. Pat. No. 2,076,971 to Soulis et al., wherein an aluminum head is cast about a precast body and wrist pin of iron or steel. However, neither of these patents nor their combined teachings illustrate the casting of a piston and swash plate assembly at opposite ends of a spherical ended rod to provide relative rotatable motion to the rod.
A method of casting end stops on a zipper utilizing a closed die is illustrated in U.S. Pat. No. 2,464,050 to Morin. The zipper stringer is merely placed in the die without locating means and the casting is made about such zipper stringer. A die insert for use in the casting of hypodermic needle assemblies is shown in U.S. Pat. No. 2,743,517 to Everett, but such castings are fixed members and are not required to flex, twist, turn or move. U.S. Pat. No. 3,384,949 to Morin discloses a method to cast a multiple part end product which may rotate around an axis perpendicular to the plane of rotation. However, the accumulated or individual teachings of these patents do not show a method of casting a double ended rod with a ball and socket arrangement cast at each end thereof.
Various disclosures teach the casting of a piston and wrist pin such as the Soulis et al. '971 patent above and the U.S. Pat. No. 3,535,986 to Daub which utilizes a die insert to control the skirt diameter of a piston. The teaching of a ball and socket cast piston is illustrated in U.S. Pat. No. 3,763,535 to Gallagher, however, this patent only teaches this piston and connecting rod assemblage. This use of die inserts for the production of rods with ball ends or movable means is further demonstrated in the U.S. Pat. No. 3,786,543 to Sato wherein a spherical element coated with a resin film is set in a die and secured in position therein against such inserts. After the die is closed, a connecting rod is cast about his spherical element and upon its removal the spherical element is freely rotatable in the connecting rod. The rotatable element in Sato '543 is not free to pivot about the race into which it is case, and the cast piston in the patent to Gallagher '535 is again just a ball ended connecting rod cast into a piston. Further, Gallagher '535 requires the cast metal to be at a pressure which will provide the required clearance between ball and piston socket.
The casting of complex or multipart assemblies in one operation is demonstrated in U.S. Pat. No. 4,062,395 to Sirmay, but the patent discloses a complex die and a finished part within a single die. A multipart casting is also taught in the U.S. Pat. No. 4,270,255 to Klimek wherein two separate parts are cast about ball ended and matable rods or tubes. In this patent a piston is cast about one rod or tube ball end and a swash plate is cast about the opposite rod or tube ball end. Each part is individually machined. These tube and rod means are then mated and the final distance between such swash plate and piston is fixed by welding of the mating rods.
The evolution and development of this casting assembly and finish machining art points out the problems of part location in a die, critical finish machining and casting to final dimensions which now culminates in the method of the present invention by which it is possible to cast a piston and swash plate assembly and then finish machine such assembly to required height, as well as, parallel, angular, and diametral surface requirements.